Bram Dorreman wrote: >When an observer describes his(or her) observation often it is >described by specifying Azimuth and Altitude. I noticed that >many people use Azimuth = 0 being North. I changed several >times in using Azimuth = 0 being either North or South >following a recomendation of people from which I expect they >should know. Here's my two cents, since everyone else has chipped in :) I have a surveying textbook that defines azimuth as "a horizontal angle measured clockwise from the local meridian using either true north or south as 0 degrees." It goes on to say that measuring from the north is the norm, but some geodetic work uses south as zero. Bate, Mueller and White's "Fundamentals of Astrodynamics" and Escobal's "Methods of Orbit Determination" both use the North = 0 convention. _______________________________________________________ Jim Varney jamesv@softcom.net Sacramento, CA